<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
</html>

<script>
    const radius = parseFloat(prompt("输入圆的半径:"));
    const area = mian(radius);
    const zhouc = 2 * Math.PI * radius;

    alert(`面积: ${area}`)
    alert(`周长: ${zhouc}`)

    console.log(`面积: ${area}`);
    console.log(`周长: ${zhouc}`);
</script>